OBJ exporter and Substance Painter

[alsomar]

When you export an obj file made with QFT to Substance Painter, the automatic UV's go nuts. But if I just open the obj file and save it with Blender, then the SP's automatic UV's work fine.

QFT obj directly loaded in SP

QFT obj opened and saved in Blender, loaded in SP

Here's a zip with both OBJ files: obj-files.zip

SP 2019.3.x creates automatic UVs for models without UVs. You only have to go to File > New
and then press "Select" to select the obj file you want to open and OK. Then Substance Painter will add an automatic UV mapping while it opens the file.

[thomthom]

Can you also attach the original SKP file?

[alsomar]

Yes, sure! But it happens with all OBJ exports I've tried.

test.zip

[alsomar]

Hi there Thomas, I hope you're safe and healty.
I have digged deeper into this and I'm quite sure this issue comes from the triangulation of the quads.
I've done several test on my own and the UV's with isolated quads on Substance Painter only appears when the obj comes from a SketchUp model with triangulated quads. If I delete the triangulation then the UV's are fine.
I'm attaching a couple of pics to clarify my point.

Quad based SketchUp model WITHOUT triangulation, exported to Substance Painter with QFT OBJ exporter

Quad based SketchUp model WITH triangulation, exported to Substance Painter with QFT OBJ exporter

[thomthom]

I'm not that familiar with Substance Painter yet. Can you do a step by step for Dummies on the steps from SketchUp to Substance? Export settings in QFT and import settings in Substance. (Along with the model above?)

[alsomar]

Hi there. I've realized what's the problem: OBJ exporter from QFT is creating the quads detached just because the quads' edges are being exported as borders. This happens only in Quads with a diagonal edge/triangulated). That makes Substance Painter and some other software like RizomUV unable get a continuous surface.